The mechanisms involved in the regulation of cyclic nucleotide concentrations, and the subsequent biological functions of the altered cyclic nucleotide levels will be studied in spermatozoa. The mechanism of action of a purified glycoprotein that elevates sperm cyclic AMP concentrations will be studied. The effect of the glycoprotein on the sperm acrosome reaction and on Ca2 ion transport will be emphasized during the next year. A low molecular weight factor associated with sea urchin eggs that elevates sperm respiration rates will be purified and characterized. The factor appears to be a peptide, and if so, it will eventually be sequenced. The potential involvement of cyclic nucleotides in the processes of capacitation and the acrosome reaction will continue to be studied using guinea pig spermatozoa as a model. In addition, the effects of female (and egg) factors on pig spermatozoa will be determined.